<?php

/*
 * This file is part of SwiftMailer.
 * (c) 2004-2009 Chris Corbyn
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Throttles the rate at which emails are sent.
 *
 * @package    Swift
 * @subpackage Plugins
 * @author     Chris Corbyn
 */
class Swift_Plugins_ThrottlerPlugin extends Swift_Plugins_BandwidthMonitorPlugin implements Swift_Plugins_Sleeper, Swift_Plugins_Timer
{
	/** Flag for throttling in bytes per minute */
	const BYTES_PER_MINUTE = 0x01;

	/** Flag for throttling in emails per second (Amazon SES) */
	const MESSAGES_PER_SECOND = 0x11;

	/** Flag for throttling in emails per minute */
	const MESSAGES_PER_MINUTE = 0x10;

	/**
	 * The Sleeper instance for sleeping.
	 *
	 * @var Swift_Plugins_Sleeper
	 */
	private $_sleeper;

	/**
	 * The Timer instance which provides the timestamp.
	 *
	 * @var Swift_Plugins_Timer
	 */
	private $_timer;

	/**
	 * The time at which the first email was sent.
	 *
	 * @var int
	 */
	private $_start;

	/**
	 * The rate at which messages should be sent.
	 *
	 * @var int
	 */
	private $_rate;

	/**
	 * The mode for throttling.
	 *
	 * This is {@link BYTES_PER_MINUTE} or {@link MESSAGES_PER_MINUTE}
	 *
	 * @var int
	 */
	private $_mode;

	/**
	 * An internal counter of the number of messages sent.
	 *
	 * @var int
	 */
	private $_messages = 0;

	/**
	 * Create a new ThrottlerPlugin.
	 *
	 * @param integer $rate
	 * @param integer $mode ,   defaults to {@link BYTES_PER_MINUTE}
	 * @param Swift_Plugins_Sleeper $sleeper (only needed in testing)
	 * @param Swift_Plugins_Timer $timer (only needed in testing)
	 */
	public function __construct($rate, $mode = self::BYTES_PER_MINUTE, Swift_Plugins_Sleeper $sleeper = null, Swift_Plugins_Timer $timer = null)
	{
		$this->_rate = $rate;
		$this->_mode = $mode;
		$this->_sleeper = $sleeper;
		$this->_timer = $timer;
	}

	/**
	 * Invoked immediately before the Message is sent.
	 *
	 * @param Swift_Events_SendEvent $evt
	 */
	public function beforeSendPerformed(Swift_Events_SendEvent $evt)
	{
		$time = $this->getTimestamp();
		if (!isset($this->_start)) {
			$this->_start = $time;
		}
		$duration = $time - $this->_start;

		switch ($this->_mode) {
			case self::BYTES_PER_MINUTE :
				$sleep = $this->_throttleBytesPerMinute($duration);
				break;
			case self::MESSAGES_PER_SECOND :
				$sleep = $this->_throttleMessagesPerSecond($duration);
				break;
			case self::MESSAGES_PER_MINUTE :
				$sleep = $this->_throttleMessagesPerMinute($duration);
				break;
			default :
				$sleep = 0;
				break;
		}

		if ($sleep > 0) {
			$this->sleep($sleep);
		}
	}

	/**
	 * Invoked when a Message is sent.
	 *
	 * @param Swift_Events_SendEvent $evt
	 */
	public function sendPerformed(Swift_Events_SendEvent $evt)
	{
		parent::sendPerformed($evt);
		++$this->_messages;
	}

	/**
	 * Sleep for $seconds.
	 *
	 * @param integer $seconds
	 */
	public function sleep($seconds)
	{
		if (isset($this->_sleeper)) {
			$this->_sleeper->sleep($seconds);
		} else {
			sleep($seconds);
		}
	}

	/**
	 * Get the current UNIX timestamp.
	 *
	 * @return int
	 */
	public function getTimestamp()
	{
		if (isset($this->_timer)) {
			return $this->_timer->getTimestamp();
		} else {
			return time();
		}
	}

	// -- Private methods

	/**
	 * Get a number of seconds to sleep for.
	 *
	 * @param integer $timePassed
	 *
	 * @return int
	 */
	private function _throttleBytesPerMinute($timePassed)
	{
		$expectedDuration = $this->getBytesOut() / ($this->_rate / 60);

		return (int)ceil($expectedDuration - $timePassed);
	}

	/**
	 * Get a number of seconds to sleep for.
	 *
	 * @param int $timePassed
	 *
	 * @return int
	 */
	private function _throttleMessagesPerSecond($timePassed)
	{
		$expectedDuration = $this->_messages / ($this->_rate);

		return (int)ceil($expectedDuration - $timePassed);
	}

	/**
	 * Get a number of seconds to sleep for.
	 *
	 * @param integer $timePassed
	 *
	 * @return int
	 */
	private function _throttleMessagesPerMinute($timePassed)
	{
		$expectedDuration = $this->_messages / ($this->_rate / 60);

		return (int)ceil($expectedDuration - $timePassed);
	}
}
